In this study, the effects of deficit irrigation, irrigation water salinity, and foliar application of seaweed extract on the mineral nutritional status of bell pepper were investigated. The experiment was conducted in a split-plot arrangement based on a randomized complete block design with three replications. Treatments included three irrigation levels (I1, I2, and I3 corresponding to 60, 80, and 100% of field capacity, respectively), three salinity levels of irrigation water (S1, S2, and S3 corresponding to 1, 3, and 5 dS m⁻¹, respectively), and different concentrations of seaweed extract foliar application (SE1, SE2, SE3, and SE4 corresponding to 0, 0.5, 1.5, and 3 g L⁻¹, respectively). The results showed that increasing the severity of deficit irrigation and salinity significantly reduced the concentration of essential nutrients, including total nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, and manganese in both leaves and fruits, while sodium content showed an increasing trend. In contrast, foliar application of seaweed extract improved plant nutritional status and increased nutrient concentrations in both organs, partially mitigating the negative effects of drought and salinity stress. In addition, in all treatments, nutrient concentrations were higher in leaves than in fruits, indicating the dominant role of leaves in nutrient uptake and accumulation. Overall, the results demonstrated that abiotic stresses disrupt plant nutrient balance, while seaweed-based biostimulants can serve as an effective strategy to improve mineral nutrition and enhance the tolerance of bell pepper under adverse environmental conditions.